What is the best initial imaging for suspected endocarditis?

From the Guidelines

Transthoracic echocardiography (TTE) is the best initial imaging modality for suspected endocarditis. When a patient presents with symptoms suggestive of infective endocarditis such as fever, new heart murmur, or embolic phenomena, TTE should be performed promptly as it is non-invasive, widely available, and can visualize vegetations, valvular damage, and complications like abscess formation [ 1 ]. TTE has a sensitivity of approximately 70% for detecting vegetations and can identify predisposing conditions such as valvular abnormalities.

Key Points to Consider

• If TTE is negative but clinical suspicion remains high, transesophageal echocardiography (TEE) should be pursued as the next step due to its higher sensitivity (>90%) and better ability to detect smaller vegetations (<3mm), prosthetic valve endocarditis, and perivalvular complications [ 1 ].
• The timing of echocardiography is important - it should be obtained early in the evaluation, ideally before or shortly after initiating empiric antibiotics, to maximize diagnostic yield and guide appropriate management decisions [ 1 ].
• TEE is recommended in all patients with clinical suspicion of IE and a negative or non-diagnostic TTE [ 1 ].
• Repeat TTE and/or TEE within 5–7 days is recommended in case of initially negative examination when clinical suspicion of IE remains high [ 1 ].
• The use of TEE has been shown to have up to a 98.6% negative predictive value (NPV) in suspected infective endocarditis [ 1 ].

Additional Considerations

• The size and other characteristics of vegetations on echocardiography have been shown to be useful in predicting complications such as peripheral embolization [ 1 ].
• In left-sided native valve S. aureus endocarditis, the presence of an intracardiac abscess and left ventricular ejection fraction < 40% on echocardiography has been shown to be independent predictors of in-hospital mortality [ 1 ].
• The ability of echocardiographic features to predict embolic events is limited, but large (≥10 mm) vegetations on the anterior mitral leaflet are associated with a higher risk of embolic complications [ 1 ].

Recent Guidelines

• A recent expert panel statement recommends the use of transthoracic and transesophageal echocardiography as the first-line imaging tests in suspected endocarditis and for assessing hemodynamic complications [ 1 ].
• Cardiac computed tomography angiography and functional imaging with FDG PET/CT have an incremental role in technically limited or inconclusive cases on echocardiography [ 1 ].

From the Research

Initial Imaging for Suspected Endocarditis

The best initial imaging for suspected endocarditis is a topic of interest due to the varying diagnostic accuracies of different imaging modalities.

• Transthoracic echocardiography (TTE) is often considered the first line of imaging due to its non-invasive nature and wide availability 2.
• A study from 2007 found that TTE with harmonic imaging had a sensitivity of 84% and specificity of 88% for detecting vegetations in patients with an intermediate likelihood of native valve infective endocarditis 2.
• However, a meta-analysis from 2017 found that harmonic TTE had a sensitivity of 61% and specificity of 94% for detecting vegetations, with a negative likelihood ratio of 0.42 3.
• Transesophageal echocardiography (TEE) is generally considered more sensitive than TTE, especially for detecting small vegetations or those on prosthetic valves 4, 5.
• A study from 2023 found that contemporary TEE imaging had improved diagnostic performance for infective endocarditis, with a sensitivity of 95.3% compared to 85.7% in 2011 6.
• The choice of initial imaging modality may depend on the patient's clinical presentation, the presence of prosthetic valves, and the availability of TEE 3, 5.

Comparison of Imaging Modalities

• TTE is generally less sensitive than TEE but is non-invasive and widely available 2, 3.
• TEE is more sensitive than TTE, especially for detecting small vegetations or those on prosthetic valves, but is more invasive and may not be necessary for all patients 4, 5.
• The use of harmonic imaging and modern echocardiography technology may improve the diagnostic accuracy of TTE 2, 3.
• Three-dimensional (3D) technology and higher frame rates/resolution may also improve the diagnostic performance of TEE 6.